Commercial Floriculture

Water quality and watering

• Good quality water is very important requirement to grow orchids successfully.
• Acceptable water sources include de-ionized distilled water and rain water.
• Watering needs depend on the potting media and the growing conditions.
• Correct watering has a direct relationship between atmospheric humidity and compost mixture.
• Fundamentally the lower the atmospheric humidity, the damper should be the compost, and the higher the humidity the lower the moisture content of the potting mixture.
• A potting media should never be wet but just evenly moist.
• Occasionally short term drying out is beneficial as this closely imitates natural conditions whereby epiphytes are subject to very dry spells.
• Although it is not advisable to water pots daily, they should all be examined frequently and if too dry, well watering or even submerging by total dipping in suggested.
• Terrestrial orchids require more water than epiphytes.
• Some orchids have heavy thick leaves with large pseudo-bulbs, these are storage devices for water, adapted by the plant to suit quite dry environments.
• These plants must be allowed to partially dry out in between watering to have a wet/dry cycle of five to seven days.
• Other varieties have thin, soft leaves, requiring more frequent watering.
• Some like Paphiopedilums do not have any pseudo bulbs at all, these therefore must be kept moist but not at all times wet.
• Generally speaking, watering twice or thrice a week would be best. When drawing up such a schedule the following factors should be kept in mind.
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• Actively growing plants need more water than resting plants.
• Large plants need more water than smaller ones or seedlings.
• Plants grown in larger pots retain moisture for longer periods than those in smaller pots and hence need less frequent watering.
• Plants require more water on a sunny day than on a cloudy day.
• Plants growing in full sun utilize water more than those in shade.
• Osmunda and coconut fiber retain moisture longer than either tree fern or bark, hence watered less frequently.
• Plants which are freshly potted should be watered very sparingly till new roots appear.
• As the number of roots appears there should be a gradual increase in the amount of watering.
• After plant maturation, watering should be completely stopped or withheld for a while to induce flowering.
• For orchids, which are collected from the wild, where they survive on a minimal supply of water obtained through rains and absorbed through the velamen roots, over watering is a hazard always to be reckoned with under cultural conditions.
• Wrinkling of the pseudo bulbs and yellowing of the leaves are due to excessive watering. Then stop watering immediately and confine to spraying only aerial parts till new root appear.
• The quality of water used, whether it is for spraying, damping down or watering direct, is of great importance. Since tap water has usually been chemically treated it should be used with caution.
• For best results, orchids need a slightly acidic water of about pH-5.
• The best water is undoubtedly rainwater except in areas with a high degree of atmospheric pollution which is common in industrial areas and in older style high density housing.
• As it is not possible to store sufficiently large quantity of freshly aerated rain water, it can be revitalized by pumping air into it win an aquarium aerator.
• The temperature of the water is important.
• If the water temperature and surrounding air temperature are equal no harm will result and slight differences either way can tolerated by healthy plants.
• Fatal, or long term damage not easily discernible at first, can result from watering with too cold water.
• Under watering will cause shriveling of the leaves and pseudobulbs and new growth will be small.
• The roots may be thin and starved. If the medium is in good condition, simply step up the frequency of watering.
• Ideally, plants should remain moist and should never be dry.
• More plants may lost to over watering that is watering too often-than by under watering.
• For most orchids, especially those with pseudobulbs, a good rule is that “If in doubt, do not water.”

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